#include<stdio.h>
#include<stdlib.h>
#include<string.h>


char* deleteCharacters(char* str, char* charSet)
{
    int hash[256];
    if (NULL == charSet)
    {
        return str;
    }
    for (int i = 0; i < 256; i++)
    {
        hash[i] = 0;
    }
    for (int i = 0; i < strlen(charSet); i++)
    {
        hash[charSet[i]] = 1;
    }
    int currentIndex = 0;
    for (int i = 0; i < strlen(str); i++)
    {
        if (!hash[str[i]])
        {
            str[currentIndex++] = str[i];
        }
    }
    str[currentIndex] = '\0';
    return str;
}

int main()
{
    char s[2] = "e";     
    char s2[5] = "hek";  
    printf("%s\n", deleteCharacters(s2, s));
    return 0;
}
